Hi Ostrosky, I have one of these weapons of standard cavalry pattern, however it is not marked to a cavalry regiment but to a Royal Engineer unit! Must be incorrect? However, the RE mounted detachment, who supported the cavalry under the title "11 Field Company of 1 RE Squadron", was formed in 1885, serving in the Egyptian War and in circa 1894 was established as part of the Cavalry Division. The unit was retitled the "Mounted Detachment RE". During the Boer War it was again renamed "1st Field Troop RE". The mounted RE went on to serve during World Wars 1 and 2 and, I believe, there after.
The sword details are:
1. Enfield produced pattern 1899 Cavalry Trooper's Sword.
2. Numerous Ordnance Marks (OM).
3. Blade markings:
a. Spine: "?/99".
b. Obverse: ricasso, "arrow over EFD" and "OM over X".
c. Reverse: ricasso, "00 over OM, '00 along side OM, '01 and ' 08". total number of OM
is 5.
4. Hilt markings:
a. Spine: "50".
b. Lower outer basket "EFD over OM".
c. Lower inner basket "6/05 over I.S.L. or 1.S.L. over RE over 5".
Your P1864 sword was a forerunner my P1899 and given that the first mounted RE unit was formed in 1885, it is likely that they were first issued with P1864 swords or, as an alternative suggestion, perhaps the P1864 swords were withdrawn from service and re-hilted hence the lack of specimens available today?
Not a lot of help but I hope interesting?
Cheers Mike R